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i am designing radio transmitter and reciever

Discussion in 'General Electronics Discussion' started by bhuvanesh, Jun 20, 2014.

  1. bhuvanesh

    bhuvanesh

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    Aug 29, 2013
    parts i have : antenna wire,magnetic wire,toroid core, 23 mhz crysrtal oscillator,some transistors ,resistors,capacitors....

    i want to design circuit to simply on and off the led by radio waves.

    could u sugest me simple circuit with to do this.. plzz.thank you in adavance
     
  2. Harald Kapp

    Harald Kapp Moderator Moderator

    9,230
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    Nov 17, 2011
    Having a schematic for a radio circuit is only half the rent. You need to get familiar with the theory behind radio transmission (modulation schemes, suitability of certain frequency ranges for different tasks) and, very important, local regulations regarding the use of the radio spectrum. Only small parts are available for public (unlicensed) use and restrictions apply to frequencies as well as to admissible power levels.

    For a circuit, Google "simple radio circuit". For background Google "radio transmission theory". Try to find a local amateur radio club (HAM club). People there are probably more than willing to share their knowledge.
     
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  3. bhuvanesh

    bhuvanesh

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    Aug 29, 2013
    Thanks sir. I am using 21 mhz frequency. I am from India. Could you say its illegal or not
     
  4. Harald Kapp

    Harald Kapp Moderator Moderator

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    Nov 17, 2011
    Sorry, I can't say. I'm not familiar with regulation in India.

    BtW: That should be 21MHz (M=Mega, m=milli).
     
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  5. bhuvanesh

    bhuvanesh

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    Aug 29, 2013
    Okay
     
  6. duke37

    duke37

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    Jan 9, 2011
    How are you going to get a 21MHz signal from a 23MHz crystal?

    21MHz is at the edge of the 15 meter amateur radio band. You should keep away from the edge in case you fall over !

    To be licenced for the amateur band you will need to pass an examination and you will need to comply with the rules as to the use. I do not know the Indian authority that deals with these matters.

    You may have some licence free bands (car fobs) which you can use but the equipment might have to be power limited and approved.
     
  7. KJ6EAD

    KJ6EAD

    1,114
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    Aug 13, 2011
    Neither is the ministry that has jurisdiction there. Good luck finding out what the rules are.

    http://www.mib.nic.in/demo.aspx
     
  8. ramussons

    ramussons

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    Jun 10, 2014
    Last edited: Jun 23, 2014
  9. Ehsan

    Ehsan

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    Jun 12, 2014
    Harald is right. The theory behind radio transmission is definitely a must.

    Get a good academic book on the principle of communication. Beware that to understand that book to an acceptable degree, you need to equip yourself with some fairly advanced mathematics topics: like derivation, Integration, time domain, frequency domain, Fourier transform, etc...
     
    Last edited by a moderator: Jun 24, 2014
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